1. Field of the Invention (Technical Field)
The present invention relates to resonant tunneling diode apparatuses and methods of manufacture and to millimeter-wave apparatuses and methods.
2. Background Art
Presently, there is no practical direct solid-state means for power generation at millimeter or submillimeter wave frequencies. IMPATT (Impact Avalanche Transit Time) and Gunn diodes can only produce significant power levels (.gtoreq.10 mW) up to frequencies of about 100 GHz with a generation efficiency of less than 1%. The only solid-state approach for generating signals above 100 GHz is to use diode frequency multipliers which further reduces efficiency by more than a factor of five.
Resonant tunneling diodes (RTDs) have demonstrated instabilities at frequencies in excess of 800 GHz. This makes them very promising for millimeter-wave oscillators. Unfortunately, in spite of the high current densities available in these devices, the RF power available is quite small. With current materials, the theoretical best performance of an individual diode is about 10 mW at 100 GHz with a 20 dB/decade rolloff. Only meager power levels of several microwatts have been demonstrated at several hundred gigahertz. The power combiner of the present invention allows for the efficient power combination of many RTDs, greatly enhancing the output power. To date, no attempts have been made to power combine the signals from multiple RTDs.